docs: def get_summary(self):
          """ Get summary of ``SNPs``.
  
          Returns
          -------
          dict
              summary info, else None if ``SNPs`` is not valid
          """
          if not self.is_valid():
              return None
          else:
              return {
                  "source": self.source,
                  "assembly": self.assembly,
                  "build": self.build,
                  "build_detected": self.build_detected,
                  "snp_count": self.snp_count,
                  "chromosomes": self.chromosomes_summary,
                  "sex": self.sex,
              }